The present invention relates generally to animal entry systems, and more specifically to a radio frequency identification (RFID) based system for controlling pet access to specific doorways and enclosed structures. The types of doorways used by pets include animal-sized entryways to human dwellings, animal dwellings, and feeding enclosures. It would be generally desirable for these entryways to have the capability to recognize and allow entry to specific animals and also to deny entry to all other animals. It would also be generally desirable for these entry systems to be easily taught or programmed to recognize specific animals, and to then operate independently, safely and reliably without the need for frequent maintenance including battery changes.
There are numerous pet access control systems in existence, many of which are capable of identifying one or more specific animals. Some of these access control systems identify the specific animals by using radio signals sent to and from suitably constructed identification collars, while others use identifying means including magnets or infra-red transmitters embedded in animal collars.
The non-radio-based animal identification systems uniformly suffer from range and orientation problems, where the magnetic based systems must have the magnet extremely close to the sensor to work. Infra-red systems require a clear line-of-sight, thus making reliable operation of infra-red based animal identification systems difficult.
The older radio-based animal identification systems were based on purely analog circuitry, and many of these systems were designed to excite an analog resonant circuit element worn by an animal and to detect the analog signal resulting from the excitation of this element. This type of circuit was dependent on the tuning of an oscillator and the tuning of the resonant element, and was also very sensitive to antenna orientation and distance, and as such was not robust. Aside from the difficulties in maintaining sufficient tuning accuracy, these systems required much more complex tuned circuitry in order to identify multiple specific animals. The circuits also were generally designed to run continuously, and as such were very power-inefficient.
One example of a purely analog circuit-based animal identification and entry control system is taught by U.S. Pat. No. 4,497,133 filed Feb. 5, 1995 entitled PET DOOR WITH CONTROL CIRCUIT THEREFOR which discloses a pet door with a control circuit whose ability to recognize a passive radio frequency ID element depends on the use of a specific resistor in the circuit. This resistor is sold along with the ID element that is used as a key tag worn by the pet. The requirement to install one specific resistor in the circuit to enable a specific oscillator frequency is a very limiting approach. This invention has no programmability other than by replacing circuit components, and no ability to recognize multiple ID elements. The invention does use a switch connected to the door to turn on the circuit when the door is pressed by an animal, thus providing operation only when necessary.
British Patent No. GB 2,305,211 filed Apr. 2, 1997 entitled Security Locking Circuit discloses a security locking circuit suitable for use with a door latch, with a passive tuned circuit functioning as the key responding to a release signal. The control system is based on a microprocessor and has the ability to learn and recognize multiple individual tuned circuits functioning as ID elements. The means for ID element characterization is dependent on the circuit characterizing and storing whatever resonant signal the ID element generates in response to the transmitted signal. This is a risky method, since there is no control on how well any one specific response signal can be differentiated from the signals generated by other tuned circuits functioning as ID elements. The invention does include power savings through the option of a sleep mode, where an animal pushing against the door would operate a microswitch that would turn the circuit on.
U.S. Pat. No. 5,992,096 filed Nov. 30, 1999 entitled CONTROLLABLE PET ACCESS SYSTEM teaches a controllable pet access system that uses one or more solenoids to unlock a pet door in response to a reader circuit scanning and receiving a signal from a passive ID element described only as an “encoded animal tag” or “encoded pet tag”. This invention uses a motion detector to activate the reader circuit, thus requiring constant power for the motion detector. The invention is also lacking programmability or means to identify multiple ID elements.
The most common application for both the radio and non-radio-based animal identification systems is for animal feeders. The majority of the inventions in this field have been for use with livestock, where there are strong economic incentives for controlling feed distribution to each animal in a pasture or similar environment. Pet feeders are a smaller portion of this inventive field, with the primary motivation being convenience.
U.S. Pat. No. 3,465,724 filed Sep. 9, 1969 entitled RECORDING AND/OR CONTROL OF THE FEEDING OF LIVESTOCK and U.S. Pat. No. 3,557,758 filed Jan. 26, 1971 entitled ANIMAL IDENTIFICATION AND CONTROL MEANS both disclose feeding enclosures with access controlled by the interaction of an animal-carried passive tuned circuit ID element with a transformer-type oscillator circuit. Both of these inventions include the output and detection of multiple frequencies to allow for a group of individual ID elements. Both of these inventions use as ID elements tuned analog circuits that must match the output frequencies of the oscillator circuit, and further the location of the ID element on the body of the animal and in relation to the transmitting and receiving coils is critical to the proper function of each of these inventions. These inventions are not turned on by an animal interacting with them but run constantly, and are thus power-inefficient.
U.S. Pat. No. 3,897,753 filed Aug. 5, 1975 entitled MEANS AND METHOD FOR SELECTIVELY CONTROLLING ANIMALS discloses an animal feeder and entry control system which in the primarily illustrated embodiments are intended for use with domestic animals, particularly pet cats. This invention does include both a food dispenser (but not food enclosure) and an enclosure door unlocking function among its embodiments. However, the driver circuit taught by this invention depends on a tuned element's effect on what are effectively the coils of a transformer to produce a change in output and thus identify a specific ID element carried by an animal. The location of the ID element in relation to the receiving coil is critical to the proper function of this invention, but there is no explicit location control taught. Additionally, this invention runs constantly, and thus is power-inefficient. This invention does not teach the use of a microprocessor or other digital device to control frequency generation or other system functions, but does teach the use of multiple ID elements responding to individual excitation frequencies.
U.S. Pat. No. 4,036,178 filed Jul. 19, 1977 entitled ELECTRONIC LOCK AND KEY SYSTEM, a continuation-in-part of U.S. Pat. No. 3,897,753, teaches a more generalized approach to an entry control system, but uses the same inefficient signal generation and detection techniques as the parent patent.
U.S. Pat. No. 4,463,706 filed Aug. 7, 1984 entitled METHOD AND SYSTEM FOR MONITORING THE DISPENSING OF DRUGS OR NUTRIENTS TO ANIMALS discloses the use of passive radio frequency ID elements carried by the animals to identify individual animals. The ID element contains memory and countdown timer circuitry that is updated by a base radio unit with information as needed. However, much of the circuitry in the animal-carried portion of this invention is actually powered by a battery.
A significant improvement over the existing art would be an animal identification and entry control system that could accurately detect multiple specific animals and could be easily and quickly programmed to recognize other animals when necessary, was powered by batteries and only drew battery power when absolutely necessary, used low-power circuitry for a minimum of battery power drain when in active operation, was durable and weatherproof enough to be used outdoors, was capable of safely limiting access to a single animal at a time, and was adaptable to entry control for applications including but not limited to entry to a feeding enclosure, entry to a human dwelling, and entry to an animal dwelling.